The next time, he promises the arresting officer, "I'll use a shotgun."

John Schriner was true to his word.

Schriner, 40, was being held yesterday in Bucks County Prison awaiting a June 29 preliminary hearing in connection with the April 25 shooting death of John M. Flaherty at the Parkway Drive-In in Haycock Township.

Flaherty, 35, who had recently become a co-owner of the well-known roadside restaurant, had earlier told Schriner, as he regularly had in the past, that there was no smoking in the restaurant.

To Schriner, described by a roommate as an angry disabled veteran who spent hours screaming at the television set or driving around back country roads to sooth his roaring psyche, that was enough to make good on the promise he had made 10 years earlier.

According to witnesses, Schriner, carrying a 12-gauge shotgun, slipped into the restaurant shortly after 9 p.m. As he stepped to the walk-up window, he lifted the gun as Flaherty turned.

"He (Flaherty) turned and pointed his finger and said, `Just a minute . . .," said Harry Grim III, Flaherty's partner, who was helping to clean up with two teen-age workers. "That's when he shot him."

Minutes later, according to Schriner's 26-year-old male roommate, Schriner laid his shotgun across the back of his car parked outside the trailer just barely a hundred yards from the restaurant.

"I said, `John, what's wrong?' He just said, `I killed him'," said the roommate. Then, as state police cars converged at the scene, the roommate, stunned, turned to Schriner again. "I said, `John, you really did it, didn't you?' He said, `I did.'"

For Schriner, a seventh-grade dropout, it was the last in an escalating series of incidents involving police. Diagnosed as a psychotic suffering from "chronic undifferentiated schizophrenia," according to court records, Schriner first found his way onto Pennsylvania police blotters for a series of minor episodes involving underaged drinking and reckless driving.

Then, in September 1981, Schriner went on a rampage in Warminster Township, Bucks County. First pistol whipping a 17-year-old boy whom he accused of having an affair with his girlfriend, Schriner fired shots at a motorist who tried to intervene before becoming involved in another fight, in which he shot a man in the leg.

It was then that Schriner uttered his chilling promise to police.

After entering a plea of guilty but mentally ill, Schriner was released after apparently serving time in Norristown State Hospital. Documents entered as part of the court record indicate that Schriner had previously received psychiatric treatment from the Veterans Administration Hospital at Coatesville, Chester County.

While in prison, Schriner was charged with sexually assaulting a minor after the 7-year-old daughter of his longtime girlfriend told school officials that Schriner had fondled her as her mother slept.

Schriner eventually pleaded guilty to corruption of minors, and indecent assault charges were dropped, according to other news reports.

For Flaherty's wife, Linda, who has struggled to regain financial footing since her husband's death, word of Schriner's past simply means that her husband should never have been shot in the first place.

"They say they don't have any more money, so they turn them out," said Mrs. Flaherty, talking to a reporter during a recent fund-raiser. "They're always protecting the bad people. Why don't they protect the good?"

Then, a bit later, she adds: "If this guy was so mad at the world, why didn't he just kill himself?"